1992 240 dl automatic 132,000 miles/overdrive switch

[rontof]

Hi All
My transmission will not shift into overdrive. The button on the shifter does not seem to work and of course the arrow on the dash is on. Funny thing is that once in a while it will shift in as I'm going along.
Am I doing any harm by driving the car 55 mph if I'm not in OD?
Thanks
Ron

[billofdurham]

First thing to check is the overdrive relay. This is located behind the centre of the dash to the left of the glovebox along with the central lock and power windows relays.

I can't remember which is which but if you pull them out one at a time and try the lock and windows you should be able to find the overdrive relay by elimination.

Try giving it a good hard flick with your finger. This sometimes encourages a reluctant relay to work.

Edit. It is the relay on the right.

Bill.